The G620 is listed at 65W, according to Wiki. If you staying with Sandy Bridge, G620T or G630T would be the lowest watt dual core. Anything below that would also be 35W but will be single core. Ivy Bridge wise, 3470T, 3240T, 3220T, G2100T are also lowest power at 35W. The absolute lowest power would be 17W but that's a $200 server chip.